Carbohydrates, proteins and lipids are all important constituents of cell membranes. Proteins, including glycoproteins, which span the lipid bilayer are called transmembrane proteins and may cross back and forth several times. While hydrophobic residues are relegated to the middle of the membrane, this crossing back and forth exposes hydrophilic residues to the internal and external milieu. (Unwin, N. et al. (1984) Sci Am 250:78-87).
Membrane proteins participate in catalyzing reactions, transporting molecules in and out of cells, receiving and transmitting intercellular messages, anchoring cells to substratum, and providing tissue-identification tags. They are important in both paracrine and autocrine signaling and may react appropriately or inappropriately in response to growth factors. In fact, cells vary in identity, character and bioactivity largely as a result of variation in their membrane proteins.
Aberrant membrane proteins have been identified in a significant number of diseases and are intimately associated with cancers. Cells displaying these aberrant proteins are often locked in continuous cell division and are characterized by their altered gene transcription, decreased growth factor requirements, loss of anchorage, and cell morphology. With aging, benign tumors arise with greater frequency even though they pose less risk. These tumors are often delineated by a fibrous capsule and contain cells that closely resemble and may function as normal cells. On the other hand, malignant cells are usually undifferentiated and characterized by their rapid proliferation and ability to metastasize.
Large-scale sequencing of the Saccharomyces cerevisiae genome has revealed an open reading frame encoding a protein designated ORM1 (GI 1620453). ORM1 has several hydrophobic domains that may associate with cell or organelle membranes.
Discovery of proteins related to S. cerevisiae ORM1 and the polynucleotides encoding them satisfies a need in the art by providing new compositions useful in diagnosis, prevention, and treatment of cancer and inflammation.